The present invention relates in general to remote control of supervisory control and data acquisition (SCADA) devices over a public communication network, and, more specifically, to providing security against unauthorized intrusion to a SCADA-like device.
SCADA devices such as programmable logic controllers (PLCs), remote terminal units (RTUs), intelligent electronic devices (IEDs), energy management system (EMS) devices, and distributed control system (DCS) devices are widely used for controlling various physical systems or plants such as electric power generation and distribution equipment and water treatment and distribution equipment. As used herein, “SCADA device” refers to any such programmable control and/or monitoring unit for interacting with sensors and/or actuators of a physical plant.
SCADA devices have evolved as specialized devices adapted to control or monitor physical systems using hardware and software resources well matched to the desired tasks. To provide a cost effective solution, a typical SCADA device has computing capabilities and memory capacity sufficient to perform its desired monitoring or control function and little else. The devices intentionally lack the flexibility (i.e., programmability) to perform a wide variety of computational and input/output functions and the memory capacity of general purpose computing devices.
In order to provide for remote control and interaction, a remote communication or networking capability has been added to many SCADA devices. For example, a modem for dial-up networking access or a network interface for including in a local area network (LAN) have been used to permit remote adjustment of parameters or other settings in a SCADA device and to remotely retrieve status or data from a SCADA device. Especially in large coordinated systems, such as an electric power grid, it is desirable to reduce management expenses by connecting SCADA devices at remote sites to a wide area network (WAN) so that device settings can be adjusted and status can be monitored from a central location. The network may include a public network such as the Internet.
Whenever remote access is available, the possibility of access by unauthorized people and of the attempted misuse or abuse of the SCADA device or the physical plant are increased. Due to the limited computational capabilities of most SCADA devices, however, it is usually not possible to deploy modern security techniques or software in them.
When remote connection is allowed via a dial-up modem, it may be possible for an unauthorized user to obtain the telephone number used in the public switched telephone network (PSTN) for connecting with the remote SCADA device. Since a SCADA device often lacks even simple security mechanisms such as password protection, the functions and/or information in the SCADA device are unprotected. SCADA devices coupled to the Internet can be especially vulnerable to hackers. The security technologies developed to protect devices on the Internet, such as encryption, security keys, and signatures for obtaining user authentication and authorization, cannot be supported by the SCADA devices.